One of Australia's most powerful union leaders has declared he is "110 per cent" behind Prime Minister Julia Gillard, warning that workers will be in for the fight of their lives if the Coalition wins this year's election.

"We support her because we want someone who's leading this nation who's prepared to make the tough calls, the hard decisions, and to cop the flak," Mr Howes told delegates at the AWU national conference on the Gold Coast today.

"Someone who's prepared to stand up to the shock jocks and billionaires and the media barons. Someone who'll fight and scrape to do the right thing for this nation.

"Like the Prime Minister, we stand up for what we believe in and we don't back down. And I'm proud to lead a union that backs her 110 per cent."

Liberal MP Jamie Briggs was quick to make light of the comment, saying on Twitter: "In a further blow to Julia Gillard, Paul Howes confirms his ongoing support."

Ms Gillard, who yesterday announced a $1 billion plan to help save manufacturing jobs, is due to address the AWU conference tonight.

Mr Howes says voters should take note of the significant public service job cuts under conservative state governments in Queensland, New South Wales and Victoria, arguing they are a sign of things to come.

"If Tony Abbott and the Coalition win the next federal election, this is the model we will see right across our nation. The experiences of failed Coalition state governments will be replicated on a national scale.

"The Liberals do not believe in a fair day's pay for a fair day's work. They do not believe in good Aussie jobs. They do not believe in looking after the battler.